Method of making waterproof heat insulating tape



Dec. 5, 1933. w R s 1,937,561

METHOD OF MAKING WATERPROOF HEAT INSULATING TAPE Original Filed Aug. 7. 1931 Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE-1 METHOD OF MAKING WATERPROOF HEAT INSULATING TAPE William R. Gillies, Chicago, 111., assignor to Union Asbestos & Rubber Company, Chicago, 111., a

corporation of Illinois Original application August 7, 1931, Serial No. 555,738. Divided and this application August 22, 1932. Serial No. 629,862 I The present invention relates to waterproof heat insulating tape and is particularly concerned with heat insulating tape of a type adapted to be spirally wrapped about a pipe or other. part intended to be insulated, such as the high temperature steam pipes of locomotives or boilers.

The present invention relates to an improvement in the heat insulating tape disclosed in my prior Patent No. 1,370,723, issued October 16, 1923.

The waterproof heat insulating tape is covered by my parent application, Serial No. 555,738, filed August 7, 1931, issued as Patent No. 1,903,106 of which the present application is a division filed pursuant to the requirement for division of the examiner. The present application relates particularly to the method and apparatus for carrying out the method of makingthe tape covered by the parent application.

Heat insulating coverings of this type, preferably consisting of an asbestos fabric sheath and an asbestos filler, perform their functions most efilciently when the heat insulating material is maintained in a dry and porous condition on account of the heat insulating property of the air spaces or interstices between the asbestos fibers.

When such a heat insulating covering becomes wet its heat insulating properties are greatly reduced and it requires a long time for the material to dry out again on account of the thickness of the covering and the inaccessibility of the inner parts of the material to air.

Furthermore, the wetting of the asbestos insulating material tends to compact and pack the fibers, and it will be evident that it is highly desirable to maintain such insulating material in its original condition.

One of the objects of the present invention is the provision of an improved waterproof covering for heat insulating tape of the class described by means of which the spirally wrapped pipe 'may be waterproofed as well as insulated against loss of heat.

Another object of the invention is the provision of an improved waterproof insulating tape comprising a protecting sheath, an insulating filling of high heat conducting value, and a covering of waterproofing material which protects the insulating material, but does not materially detract from its heating insulating properties.

Another object of the invention is the provision of a waterproof and heat insulating covering for pipes, by means of which the heat insulation characteristics of the covering are materially increased and improved by forming an air tight fibers and in the interstices of the heat insulating material so as to form a dead air space between the outer layer of the covering and the pipe.

Another object of the invention is the provision of an improved method of waterproofing heat insulating tape of the type covered by my prior application and other similar types.

Another object of the invention is the provision of an improved waterproof covering for pipes, in which the waterproofing is so located that it 'efiects a complete waterproof covering for the insulating material, but'the insulating material protects the waterproof covering from. the high temperatures which are present in the pipes to which this material is usually applied.

Other objects and advantages of the invention will be apparent from the following description and from the accompanying drawing, in which similar characters of reference indicate similar parts throughout the several views.

Referring to the single sheet of drawing:

Fig. 1 is a fragmentary elevational view of a pipe covered with heat insulating material constructed according to the present invention;

Fig. 2 is a diagrammatic elevational view of one form of apparatus which may be used for" waterproofing the present tape, with the tape shown in cross section; and I Fig. 3 is a fragmentary sectional view taken on the plane of the line 3-3 of Fig. 1 looking in the direction of the arrows.

In the drawing the insulating tape is indicated in its entirety by the reference character A, the pipe by the reference character 13 and the securing devices by the reference character 0. The

tape A preferably consists of a flattened tube or sheath 10 -which is preferably formed of a heat insulating and heat resisting material such as a textile fabric, the woof and warp of which are in the form of threads of asbestos fiber- The threads of which the sheath fabric is woven may consist of relatively long asbestos fibers; in which case it may not be necessary or desirable to employ any other fibers, but in order to make this fabric out of cheaper short fiber asbestos it is often desirable to include a small percentage of long animal or vegetable fiber such as cotton, to give the threads greater tensile strength.

The sheath shown in Fig. 10 is woven in tubular form, but in some embodiments of the invention the-sheath may consist of a strip of fabric, the edges of which are sewed together in any convenient manner to form a tube. The tape shown in the present drawing is to be regarded as exemplary of one of the many forms of my insulating tape-and various forms of weave may be used in making the sheath 10 such as the ordinary 5 conventional weave, a diagonal weave, etc.

The width of the sheath 10 is preferably greater than its thickness and the sheath is preferably filled with a multiplicity of independent ropes or rovings 11 comprising large soft rovings of asbestos fibers which are disposed side by side in the but the asbestos ropes or rovings presentmany advantages over a single flat asbestos filling.

The tape so constructed comprises a substantially flat insulating member, the filling of which provides a layer of heat insulating material of substantially uniform characteristics and the sheath of which provides a protective covering. The material is ordinarily applied to pipes B by wrappingthe tape spirally about the pipe in such manner that the lower side 12 of the tape engages the pipe, the upper side 13 of the tape being visible and the edges 14 and 15 of the tape engaging each other to form a substantially continuous covering for the pipe, of substantially uniform thickness and heat insulating value.

Referring to Fig. 3, the waterproof insulating tape constructed according to the present invention preferably has a layer of waterproofing material extending from a point 1t between the edges 14, 15 along the outer side 13 of the tape to a point 17 between the opposite edges 14 and 15; This waterproof layer preferably covers only the outside of the fabric sheath 10 in such manner as to render the outside of the covering waterproof without impregnating any of the filler 1] or affecting the heat insulating qualities of the inside of the sheath 10.

Referring to Fig. 3; it will be observed that the waterproof layer not only extends across the outside of the sheath but over the edge of the sheath to a point so located that the adjacent edges of the tape have their waterproof layers in contacting engagement with each other to provide the outside of the pipe with a substantially continuous layer of waterproofing material without any cracks.

In some embodiments of the invention practi I thirds the thickness of the tape.

The waterproofing material employed upon the present tape preferably consists of a material which is adapted to effect a substantially waterproof joint between the edges of the tape when the adjacent waterproof layers on the edges'are brought into contacting relation.

Furthermore, the. waterproofing should preferably be of a-type adapted to cover the outside of the sheath and effect a relatively permanent air tight and waterproof covering without being 'absorbed into the interior of the sheath and without impregnating any more of the a bestos material than is absolutely necessary. I prefer to use a relatively thick composition having a rubber latex base so as to provide a rubber covering for the outside of the insulated pipe and a composition of this type is adapted to accomplish the results desired in a most emcient manner.

A suitable composition may be made and applied as follows:

The latex is preferably made alkaline and vulcanized in the presence of sulphur and a suitable accelerator, by the application of heat, at a lower temperature than the usual vulcanization temperature. The vulcanized product is then applied to the tape as described, and the evaporation of the liquid from the composition deposits the vulcanized rubber on the tape.

The waterproof layer 18 of rubber merely covers and is attached to the outermost fibers of asbestos and the inside of the sheath is not impregnated as would be the'case if a relatively thin liquid covering were sprayed on the asbestos covering. The adjacent edges 16 and 17 of the waterproof covering 18 engage each other and such a rubber covering has theproperty of effecting a substantially water tight joint between the turns of spirally wrapped tape by means of the rubber to rubber contact of these edges. It should also be noted that the rubber is kept out of contact with the pipe B since pipes to which it is applied are often at very high temperatures, such as pipes that are used for conveying superheated steam, and if the rubber covering were applied to both sides of the tape the rubber would be burned by contact with the hot pipe, whereas in the present case the rubber is protected by the intervening layer of asbestos insulating material.

Furthermore, the rubber layer forms an air tight and waterproof covering over the entire length of the pipe, thereby forming a dead air space between the rubber and the pipe which greatly enhances the insulating value of the tape covering and the insulating properties of the tape are continuously maintained, in the same condition because the tape cannot become wet with water, oil or any liquid. I

In some embodiments of the invention other waterproofing compounds may be used in the same Other flexible waterproofing compounds which may be used, are compositions including petroleum tar, coal tar, asphaltum, resins, varnish or other thick gums insoluble in water. Particular waterproofing coatings may be selected for the specific chemical conditions to be encountered.

Referring to Fig. 2, this is a diagrammatic view of an apparatus for waterproofing tape of this type. The apparatus may consist of a reservoir 20 having a supply of waterproofing compound 21 with a free surface such as is shown at 22. Reservoir 20 may be provided with bearings 23 for receiving the trunnions 24 of, a substantially cylindrical roller 25 having radially projecting flanges 26. The roller 25 has its cylindrical surface 27 dipping in the rubber latex composition 21 and the annular surface 28 on the flanges 26 also dips in the composition.

The roller 25 is adapted to cooperate with a cylindrical roller 29 which is rotatably supported upon trunnions 30 and the two rollers may be geared together by gears 31, 32. The roller 29 is preferably spaced from the peripheral surfaces 33 of the flanges 26 to prevent the roller 29 from becoming covered with rings of waterproofing composition and the roller 29 is intended to maintain the tape A in proper engagement with the roller without causing the waterproofing to be applied to the side 12 of the tape A.

It will be observed that the flanges 26 extend upward on the edges of the tape to a point slightly past the center of the tape and as the tape is fed between the rollers 29 and 25 the thickrubber latex composition 21 will be applied to the side 13 and the edges 14 and 15 up to the points 16 and 17. The composition is adapted to dry to form a waterproof rubber covering upon these portions of the tape and the tape may be wrapped about the pipe B to provide a continuous waterproof covering as well as a heat insulating covermg.

The tape is preferably secured to the pipe B by a plurality of peripheral bands, such as, for instance, the U-shaped wire securing device C which has its two ends 34, inserted under the yoke of the U-shaped wire and bent over to secure the wire tightly about the tape. It will thus be observed that I have invented an improved waterproof heat insulating tape and an improved method of making tape of the class described. The waterproofing might be applied in many different ways and the present apparatus is merely exemplary of one of the forms of apparatus that may be used.

It will be evident that the waterproofing may also be applied by hand, if desired, but the present tape is preferably supplied to the trade with the waterproofing already applied, as described; in such manner as to waterproof the insulation most effectively when it has been applied to the pipe.

While I have illustrated a preferred embodiment of my invention, many modifications may be made without departing from the spirit of the invention, and I do not wish to be limited to the precise details of construction set forth, but desire to avail myself of all changes within the scope of the appended claims.

- Having thus described my invention, what I claim as new and desire to secure by United States Letters Patent is: l. The method of waterproofing heat insulating tape which comprises continuously applying a waterproofing material to one side of said tape and to the edges of said tape in such manner that a continuous waterproof layer will be formed when the tape is spirally wrapped upon another 'member.

2. The method of waterproofing heat insulating tape which comprises continuously applying a waterproofing material to one side of said tape and to the edges of said tape in suchmanner that a continuous waterproof layer will be formedwhen the tape is spirally wrapped upon another member, said waterproofing material comprising a. relatively thick composition having a rubber latex base. i

3. The method of waterproofing heat insulating tape which comprises applying a waterproofing material comprising a thick viscous rubber latex compound to one side of the tape in such manner that a continuous waterproof layer will be formed when the tape is spirally wrapped upon another member, said compound substantially covering the one side and edges of the tape without impregnating the major portion of the heat insulating material of the tape.

WILLIAM R. GILLIES. 

